Roman's 4GR V6 Carina discussion thread

[xsspeed]

i love how we all now know way too much about 4gr's and 1nz's thanks to romandayf

[kpr]

1 hour ago, xsspeed said:

would be interesting to see if you could, I'm guessing either the cranks are mounted higher in a 4gr or the piston compression height is significantly different between the two (or both) to account for such stroke difference. solution is only a custom set of rods away if need be

probably just the usual shorter block height on the 4gr,   usually a toyota / most manufacturers move. save some material cost and make engine bit shorter.    so yeah  longer rods  would be needed.  probably giving a rod ratio well over 2.    bigger bore, bigger valves bit more capacity.  probably blow the budget, but would be pretty cool if the crank did swap over

[Roman]

Yep so the crank could swap.

Ideal starting point is the 5GR motor.

Its 2500cc with 2GR sized bore and a crazy tiny stroke. But this motor was only available in China for whatever reason.

 

 

[xsspeed]

Man I love how I can draw RB comparisons, RB24 is also a unicorn with rb26 bore and rb20 crank, only carb'd and only available in malaysia

[Raizer]

1 hour ago, Roman said:

Ideal starting point is the 5GR motor.

Its 2500cc with 2GR sized bore and a crazy tiny stroke. But this motor was only available in China for whatever reason.

$5200 inc DHL shipping from AliExpress haha

[keltik]

Full development on the 4GR then build a 5GR to drop in there once we know it all works.

/I'm told a 13B would happily do the power and rpm numbers you're looking for

[Atex]

Did the Honda J30A4 engine cross your radar when looking for light weight v6 engines?

[MS51HT]

No doubt you've already done the comparison somewhere - but thought it was interesting to look at the 2GR, 3GR and 4GR engine specs side by side (or more accurately top on top)

2GR

[Roman]

There are some other interesting short stroke contenders, will add in the Alfa 155 DTM motor for interests sake.
These are all 2500cc V6
Looks like 2MZFE is the closest in spec to the alfa motor interestingly enough.
MZ series motors suck though.

Bore size:

4GR:        83mm
VQ25HR: 85mm
2MZFE:    87.5mm
Alfa:         88mm 

Stroke length:
4GR:         77mm
VQ25HR:  73.3mm
2MZFE:    69.2mm
Alfa:         68.3mm
 

[GARDRB]

14 hours ago, Roman said:

Looks like 2MZFE is the closest in spec to the alfa motor interestingly enough.
MZ series motors suck though.

Bore size:

4GR:        83mm
VQ25HR: 85mm
2MZFE:    87.5mm
Alfa:         88mm 

Stroke length:
4GR:         77mm
VQ25HR:  73.3mm
2MZFE:    69.2mm
Alfa:         68.3mm
 

 

Wash your mouth out. VZ motors suck, MZ are at least alloy

[Roman]

Low compression.

No aftermarket parts.

Stupid scissor cam gear thing.

Dunga power as standard.

No vvti on the 2500cc 

Cheap though. Likely all have a zillion km on them though.

If cams and valvesprings were available id consider it.

Would bolt to j160 is a feather in its cap.

[shrike]

How easy/cheap is it to get spare heads for these?

Any cheap dead motors around that you can play with first?

[Roman]

Yeah theres a bunch of mark x at pickapart. 

Id not be surprised if all of the motors are fucked and thats why they are there. My motor had not that many kms and its so absolutely full of caked up shit. 

Id not be surprised if all these cars start going extinct around 200,000km.

Direct injection without port injection makes for a short lifespan.

 

[Honda Ass Dragger]

Honda F1 Cylinder Head Sections from both a V10 and V8

[~Slideways~]

On 21/04/2023 at 12:07, Roman said:

Yeah theres a bunch of mark x at pickapart. 

Id not be surprised if all of the motors are fucked and thats why they are there. My motor had not that many kms and its so absolutely full of caked up shit. 

Id not be surprised if all these cars start going extinct around 200,000km.

Direct injection without port injection makes for a short lifespan.

 

I wonder if some periodic water injection would help?

[tortron]

My research into squishbands is that the sharp edge promotes a turbulent mix when it gets squished

My GN head had less detonation when I rounded them. But it had other things going on with the piston shape. Nothing negative happened, there was also less carbon in thrle head compared to stock sharp band 

[Roman]

Interesting. Im guessing a lot of these things are necessary for stratified charge, but less relevant when youve got high up port injectors. 

Will eventually buy another motor or 2 to try some other stuff too. 

[Roman]

On 23/04/2023 at 13:41, ~Slideways~ said:

I wonder if some periodic water injection would help?

Not sure. I guess running a catch can would help, its probably a lot to do with oily buildup from that.

But the valves were almost road cone shaped with shit piled on top.

[Roman]

Some results from the 3500cc motor running same cams as I'm planning. 

405whp on E85 at 7500rpm.
 

So if I could manage that same power/litre would be around 290hp at wheels. Yikes!
Hopefully keeps pushing powerband up more with smaller motor.
The motors are obviously a bit different so there's no assurance mine would react the same. 

Also worth noting that these results are great but it sounds pretty yuck. Would probably sound nicer with some longer manifolds rather than short 3-1 setup. 
I'm still considering how I could fit a 6-1 manifold after @h4nd poisoned my brain with amazing engine noises with that V12 video.

 

[xsspeed]

Sounds yuck cos hasn't cracked 9k rpm